Mary has 20 biscuits in a tin there are 11 plain biscuits 7chocolate biscuits 2 currant biscuits sue takes at random 2 biscuits
1 answer:
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Step-by-step explanation:
<u>Permutations</u>:
n<em>P</em><em> </em>r = n!/(n + r)!
<u>Combinations</u>:
<em>nCr</em> = n!/(n - r)!r!
c - combination
p - permutations
Since in both the problems they are looking for different groups, it is a combination problem. the order in which the people were selected in each group is not important, what is required are different groups.
<u>A.</u>
n = 51
r = 3
51<em>C</em><em> </em>3 = 51! / ((51 - 3) ×3!)
<em>51C</em><em>3</em><em> </em><em>=</em><em> </em><em>2</em><em>0</em><em> </em><em>8</em><em>2</em><em>5</em><em> </em>groups
<u>OR:</u>
<em><u>B</u></em><em><u>.</u></em>
